This application relates to a dentally retained intra-oral appliance worn at night for treatment of snoring and obstructive sleep apnea. The appliance maintains the patient""s mandible in an anterior, protruded position to prevent obstruction of the pharyngeal airway. The appliance allows a limited degree of lateral movement of the mandible relative to the upper jaw in the protruded position to prevent aggravation of the tempromandibular joint and associated muscles and ligaments.
Snoring and obstructive sleep apnea are typically caused by complete or partial obstruction of an individual""s pharyngeal airway during sleep. Usually airway obstruction results from the apposition of the rear portion of the tongue or soft palate with the posterior pharyngeal wall. Obstructive sleep apnea is a potentially lethal disorder in which breathing stops during sleep for 10 seconds or more, sometimes up to 300 times per night. Snoring occurs when the pharyngeal airway is partially obstructed, resulting in vibration of the oral tissues during respiration. These sleep disorders tend to become more severe as patients grow older, likely due to a progressive loss of muscle tone in the patient""s throat and oral tissues.
Habitual snoring and sleep apnea have been associated with other potentially serious medical conditions, such as hypertension, ischemic heart disease and strokes. Accordingly, early diagnosis and treatment is recommended. One surgical approach, known as uvulopalatopharyngoplasty, involves removal of a portion of the soft palate to prevent closure of the pharyngeal airway during sleep. However, this operation is not always effective and may result in undesirable complications, such as nasal regurgitation.
A wide variety of non-surgical approaches for treating sleep disorders have also been proposed including the use of oral cavity appliances. It has been previously recognized that movement of the mandible (lower jaw) forward relative to the maxilla (upper jaw) can eliminate or reduce sleep apnea and snoring symptoms by causing the pharyngeal air passage to remain open. Several intra-oral dental appliances have been developed which the user wears at night to fix the mandible in an anterior, protruded (i.e. forward) position. Such dental appliances essentially consist of acrylic or elastomeric bite blocks, similar to orthodontic retainers or athletic mouthguards, which are custom-fitted to the user""s upper and lower teeth and which may be adjusted to vary the degree of anterior protrusion.
U.S. Pat. No. 4,901,737, which issued to Toone on Feb. 20, 1990, exemplifies the prior art. Toone discloses an intra-oral appliance for reducing snoring which repositions the mandible in an inferior (open) and anterior (protrusive) position as compared to the normally closed position of the jaw. Once the dentist or physician determines the operative xe2x80x9csnore reduction positionxe2x80x9d for a particular patient, an appropriate mold is taken of the maxillary dentition and of the mandibular dentition for formation of the appliance template. The Toone appliance includes a pair of V-shaped spacer members formed from dental acrylic which extend between the maxillary and mandibular dentition to form a unitary mouthpiece. In an alternative embodiment of the Toone invention, the spacer members are formed in two pieces and a threaded rod is provided to enable adjustment of the degree of mandibular protrusion or retrusion after the mouthpiece is formed.
European patent application No. 0,312,368 published Apr. 19, 1989 also discloses an intra-oral device for preventing snoring. This device consists of a U-shaped mouthpiece which conforms to the upper dental arch of the user and includes a sloped, lower ramp for engaging the mandibular dentition. Normal mouth motions, such as the clenching of the jaw, will cause some of the mandibular dentition to engage the underside of the ramp, thereby camming the lower jaw forward to increase the spacing between the base of the tongue and the posterior wall of the pharynx.
While prior art dental appliances have proven effective in maintaining the mandible in a protruded position to improve airway patency, they often result in undesirable side effects. One of the most common side effects is aggravation of the tempromandibular joint and related jaw muscles and ligaments, especially in individuals who have a tendency to grind their teeth during sleep. Aggravation of the tempromandibular joint has been associated with a wide variety of physical aliments, including migraine headaches. Accordingly, many individuals suffering from sleep apnea and snoring disorders are not able to tolerate existing anti-snoring dental appliances for long periods of time.
The need has therefore arisen for a dental appliance for treatment of snoring and sleep apnea which will maintain the mandible in a preferred anterior position, but which will also allow a limited degree of lateral excursion of the mandible relative to the upper jaw to avoid discomfort to the tempromandibular joint and related muscles and ligaments.
In accordance with the invention there is provided an intra-oral dental appliance to be worn by a patient during sleep for treatment of obstructive sleep apnea and snoring. The dental appliance includes an upper member conforming to the patient""s maxillary dentition, a lower member conforming to the patient""s mandibular dentition, and connecting means for releasably coupling the upper and lower members together to maintain the lower member in an anterior, protruded position relative to the upper member. The connecting means includes adjusting means which is manually adjustable to incrementally vary the degree of anterior protrusion of the lower member relative to the upper member. The connecting means is loosely coupled to the lower member to permit a limited degree of lateral movement of the lower member relative to the upper member in the anterior, protruded position.
The upper and lower members are preferably flexible bite blocks formed from elastomeric material. Preferably the connecting means is secured to anterior regions of the upper and lower bite blocks and includes a first element bonded to an undersurface of the upper bite block; a second element bonded to an upper surface of the lower bite block; and an elongated connector for releasably coupling the first and second elements together.
Preferably the connector has an upper end which is fixedly connectable to the first element and a lower end which is loosely connectable to the second element to permit the limited degree of movement of the lower bite block relative to the upper bite block in the protruded position. Advantageously, the second element has an internal cavity for capturing the lower end of the connector, the cavity having an opening formed on an upper surface of the second element through which the connector extends. The connector preferably consists of a stylus having a threaded upper portion and an enlarged head formed on its lower end having a diameter exceeding the size of the cavity opening.
The upper element preferably consists of a retention plate having a plurality of internally threaded apertures formed therein for releasably receiving the threaded portion of the stylus. The threaded apertures are spaced apart at regular intervals to enable incremental adjustment of the degree of anterior protrusion of the lower bite block relative to the upper bite block.
The second element preferably consists of a guide box having an upper surface, vertical sidewalls, and an open bottom end, the guide box having a hollow area between the sidewalls comprising the internal cavity and an aperture formed on the upper surface comprising the cavity opening. The dimensions of the cavity preferably exceed the size of the stylus head and the cavity opening is laterally elongated to permit a limited degree of lateral movement of the lower bite block relative to the stylus. The guide box further includes a base plate for releasably covering the guide box bottom end, the base plate having an aperture formed therein to permit access to the stylus head captured within the internal cavity.
The retention plate and the base plate each further include a plurality of retention apertures spaced around the periphery thereof to enable acrylic to flow through the plates when the plates are initially bonded to the upper and lower bite blocks.
Preferably, the upper and lower bite blocks further include a first pair of bite pads formed on the undersurface of the upper bite block and projecting downwardly therefrom and a second pair of bite pads formed on an upper surface of the lower bite block and projecting upwardly therefrom for slidably engaging the first pair of bite pads. The bite pads are located in a posterior region of the bite blocks to limit closure of the patient""s jaw.
A connecting assembly for use in an intra-oral dental appliance to be worn by a patient during sleep for treatment of obstructive sleep apnea and snoring is also disclosed, the dental appliance comprising an upper bite block conforming to the patient""s maxillary dentition and a lower bite block conforming to the patient""s mandibular dentition. The connecting assembly includes a first element securable to an undersurface of the upper bite block; a second element securable to an upper surface of the lower bite block; and an elongated connector for releasably coupling the first and second elements together to maintain the lower member in an anterior, protruded position relative to the upper member, the connector having an upper end which is securely connectable to the first element and a lower end which is loosely connectable to the second element to permit a limited degree of lateral movement of the lower bite block relative to the upper bite block in the protruded position.
A method of treating snoring and obstructive sleep apnea by adjustably maintaining a patient""s mandible in a protruded position is also disclosed comprising the steps of (a) casting an upper bite block by taking a mold of the patient""s maxillary dentition; (b) casting a lower bite block by taking a mold of the patient""s mandibular dentition; (c) securing a first retention element to the undersurface of the upper bite block in an anterior region thereof; (d) securing a second retention element to an upper surface of the lower bite block in an anterior region thereof, the second element comprising an upwardly projecting connector having a lower end loosely captured within a cavity formed in the second element; (e) determining the preferred degree of mandibular protrusion required to alleviate the patient""s sleep apnea and snoring symptoms; and (f) releasably securing an upper end of the connector to the first retention element at a fixed position corresponding to the patient""s preferred degree of mandibular protrusion as determined in step (e).